Apparatus for opening flattened tubes of flexible sheet material

ABSTRACT

THE SUPERIMPOSED LAYERS OF THE ENDS OF FLATTENED FLEXBLE TUBES USED IN BAG MAKING ARE FIRST SEPRATED GRADALLY BY SUCTION MEANS OPERATING ON THE OPPOSITE SIDES OF THE FOLDED TUBES ADJACENT THE ENDS THEREOF AND ARE THEREAFTER OPENED RAPIDLY. THE SUCTION MEANS COMPRISE OTHER SUCTION TABLES WHICH CAN BE MOVED APART DURING STATIONARY PERIODS IN STEP-CONVEYANCE OF THE TUBES, OR WHERE THE TUBES ARE CONVEYED CONTINUOUSLY, COUNTER-ROTATING SUCTION ROLLERS OR BELTS. AFTER INITIAL SEPARATION OF THE LAYERS THE TUBES ARE PASSED TO A SUBSEQUENT STATION WHERE THE ENDS ARE RAPIDLY OPENED COMPLETELY.

NOV. 9, 1971 ACHELPOHL 3,618,476

APPARATUS FOR OPENING FLATTENED TUBES 0F FLEXIBE SHEET MATERIAL Filed Aug. 27, 1968 5 Sheets-Sheet l FIG.1

II- t INVENTOR B Fritz ACH ELPOHL if A I I 9 ATTORNEYS 9, 1971 F. ACHELPOHL APPARATUS FOR OPENING FLATTENED TUBES OF FLEXIBE SHEET MATERIAL 5 Sheets-Sheet 2 Filed Aug. 27, 1968 9: INVENTOR FritzACHELPOHL lozum 4; Pour ATTORNEYS 1971 F. ACHELPOHL' APPARATUS FOR OPENING FLATTENED TUBES OF FLEXIBE SHEET MATERIAL 5 Sheets-Sheet 5 Filed Aug. 27, 1968 L H mm M l VC m m Z w P YDI. w

ATTORNEYS NOV. 9, 1971 ACHELPOHL 3,618,476

APPARATUS FOR OPISNLNG FLAT'LUNED 'ruuus 01- FLEXIBE SHEET MATERIAL Filed Aug. 27, 1968 5 Sheets-Sheet FIG.6

INVENTOR Fritz ACHELFOHL grwuwa ATTORNEYS Nov. 9, 1971 F ACHELPOHL 3,618,476

, APPARATUS FOR OPENING FLAITENEJ) TUBES 0F FLEXIBE SHEET MATERIAL Filed Aug. 27, 1968 5 Sheets-Sheet 5 FIG. 8 IE INVENTOR Fritz ACHELPOHL ATTORNEYS United States Patent 3,618,476 APPARATUS FOR OPENING FLATTENED TUBES OF FLEXIBLE SHEET MATERIAL Fritz Achelpohl, Wulfekuhle, Germany, assignor to Windmoller & Holscher, Lengerich, Westphalia, Germany Filed Aug. 27, 1968, Ser. No. 755,707 Claims priority, application Germany, Sept. 1, 1967, P 16 11 701.4 Int. Cl. B31b 1/00 US. Cl. 93-8 3 Claims ABSTRACT OF THE DISCLOSURE The superimposed layers of the ends of flattened flexible tubes used in bag making are first separated gradually by suction means operating on the opposite sides of the folded tubes adjacent the ends thereof and are thereafter opened rapidly. The suction means comprise either suction tables which can be moved apart during stationary periods in step-conveyance of the tubes, or where the tubes are conveyed continuously, counter-rotating suction rollers or belts. After initial separation of the layers the tubes are passed to a subsequent station where the ends are rapidly opened completely.

BACKGROUND OF THE INVENTION This invention relates to an apparatus for opening flattened tubes of flexible sheet material.

In the manufacture of bags and sachets of prefabricated pieces of flexible tube, cross-bottoms are pulled on and laid by bottom-making machines which open the tightly adjacent (closed) layers of the tube. at the ends thereof, then pull on the ends, then effect the bottom folding.

The step of opening the tube ends causes great difliculties at high outputs and which must be very reliable, more particularly in cases in which the tubes to be opened are made of plastics films or foils. A known method is for rotating suckers which engage both sides of the tube ends to open the same so far in one working step that the tools which spread or pull on the cross-bottoms can be introduced reliably into the ends of tubes. In the processing of flexible tubes made of platsics films or foils in particular this method often causes disturbances in operation due to special physical properties of such films or foils.

To open the tightly adjacent layers of the tube, the atmospheric pressure acting on the layers must be overcome. Opening is more reliable in proportion as the initial gap through which air can flow between the layers and equalise the pressure with atmosphere is longer, and therefore larger, at the time when the layers move apart from one another. In the case of papers, with their natural stiffness and reduced stretch, the initial gaps occurring when the suckers separate the layers from one another are of adequate length, so that the pressure is equalised fast enough, but plastic foils, being highly flexible and resilient, disengage from one another only very near the suction orifices of the suckers, with the result that, as they disengage from one another, the gaps left are very small and permit only slow pressure equalisation. Consequently, at high production speeds the pull required for the suckers exceeds the suction forces, so that the suckers disengage from the foils and the tube ends remain unopened.

SUMMARY OF THE INVENTION It is an object of the invention to provide very reliable opening of the tube ends at high production speeds.

3,618,476 Patented Nov. 9, 1971 According to one aspect of the invention there is provided an apparatus for performing a method of opening an end of a flattened tube of flexible sheet material in which the adjacent layers of the sheet material on either side of the flexible tube at said end are separated from one another slowly by a few millimetres by suction means acting on both sides of the tube before opening the tube end completely.

The initial disengagement, or partially opening, step, which precedes the full opening step and which, because of the small amount of opening and the relatively long time taken allows atmospheric air sutficient time to penetrate through the small gaps between the layers and equalise the pressure ensures that the tube ends are reliably opened at the subsequent station at high production speeds.

To accelerate the initial opening or disengagement step, compressed air may be blown into the gaps between the tube layers. Preferably, the air blown in is ionised air in order to neutralise any electrostatic charges which may be present in the foils and which may make the layers either stick to one another or reclose after the initial opening step.

The unopened film layers may be disengaged from one another at the tube. ends by being moved parallel and in opposite directions to one another over all or a large proportion of the width of the tube. The disengagement of the unopened film layers may start at one side fold of the tube and progress over substantially the whole width of the tube. This variation has the great advantage that the initial disengagement proceeds like a peeling operation and starts at a part of the tube--i.e., at the side foldwhere the resilient stress is such that the layers are not tightly adjacent one another anyway. The instantaneous force required from the suckers is very small, so that initial disengagement proceeds very reliably.

It has been found by experience that after the layers have been disengaged at the tube end, it is not essential for subsequent rapid opening of the layers that the gap resulting from the initial disengagement should remain open until the start of the opening step. The air entering through the gap left by initial disengagement ensures that the layers do not settle together again and, therefore, that the tube will subsequently be opened rapidly.

According to a further aspect of the invention an apparatus is provided for performing the above method including means for advancing flattened tubes of flexible sheet material stepwise and means for opening the ends of the tubes during the stationary periods of the tubes comprising a pair of suction tables adapted to engage opposite sides of a tube end, over a major proportion of the tube width, during a stationary period of the tube and having a drive means arranged to move the suction tables a few millimetres away from one another gradually during substantially the whole stationary period of the tube.

This apparatus is 'of use for stepwise bottom-makers which perform the steps of forming the bottom substantially during the stationary periods of the tubes.

According to a yet further aspect of the invention an apparatus is provided including means for conveying flattened tubes of flexible material at a uniform rate in a conveying direction and including a pair of suction rollers arranged to engage opposite sides of the tube and which rotate in the direction of conveyance of the tubes and at a velocity corresponding to the speed of conveyance of the tubes, the rollers providing a suction zone which extends through only a small angle in the direction of rotation from the contact plane between the suction rollers.

When the tube ends pass through between the suction rollers, the same disengage the layers from one another at the end of the tube continuously along the suction zone, allowing air to come between the layers.

The periphery of the suction rollers is preferably equal to the spacing, or to an even multiple thereof, at which the tubes are advanced in the bottom-maker; and the set of suction orifices in the peripheries of the suction rollers or in that part thereof corresponding to a spacing extends only over a peripheral distance equal to or less than the maximum tube width to be dealt with, the spacing and therefore the peripheries of the suction rollers being so devised that the angular zone devoid of suction orifices is at least equal to the angular zone of the suction zone. This step ensures that the negative pressure in the suction Zone is always fully operative at the entry of the tube thereinto.

According to a yet further aspect of the invention an apparatus is provided including means for continuously conveying flattened tubes of flexible sheet material, a pair of stationary suction tables extending in the direction of conveyance of the tubes, and having adjacent faces formed with suction slots, said faces diverging in the direction of conveyance by a few millimetres and being covered by suction belts formed with suction holes and arranged to engage the layers of sheet material on opposite sides of the tubes, and to move with the speed of conveyance of the tubes.

The diverging suction belts suck both sides of the tube ends and as the same move between the suction tables, disengage the layers slowly by a few millimetres from one another. Preferably the suction tables extend over the whole width of the tubes, so that the time during which the layers are initially disengaged from one another corresponds to substantially one working stroke of the bottommaker. Experience shows that this is sufficient time to achieve pressure equalisation via the gap between the layers.

The apparatus may form a special working station in a bottom-maker and can precede any known station for drawing on and laying the cross-bottoms, to ensure the necessary reliability of operation in such station in the opening of, for example plastics film tubes.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 shows partly in section and partly in side elevation an embodiment of the invention in combination with a stepwise bottom-maker;

FIG. 2 is a section on the line IIII of FIG. 1;

FIG. 3 is a view in side elevation, on the line IIIIII of FIG. 4, of a further embodiment in combination with a continuous bottom-maker;

FIG. 4 is a section on the line IVIV of FIG. 3;

FIG. 5 is a section to an enlarged scale on the line V--V of FIG. 3;

FIG. 6 is a section on the line VIVI of FIG. 3;

FIG. 7 is a plan view, substantially on the line VII VII of FIG. 3, of a detail;

FIG. 8 is a view in longitudinal section, on the line VlIIVIII of FIG. 9, of another embodiment in combination with a continuously operating bottom-maker, and

FIG. 9 is a plan view of the embodiment of FIG. 8.

DESCRIPTION OF THE PREFERRED EMBODIMENTS The bottom-maker in which the apparatus shown in FIGS. 1 and 2 is used conveys portion S of a flexible tube stepwise, in the direction indicated by an arrow a, through the agency of gripper chains 1 whose grippers 2 engage with a longitudinal edge of the flexible tube. The same is therefore advanced in a transverse position by a distance t at each step, stationary periods being interposed between the steps. This stepwise motion of the gripper chains is of course achieved by a stepping mechanism in the gripper chain drive. The tubes go between parallel guide bars 3 disposed on both sides of the tube transverse central plane at a distance from one another such that the tube ends project laterally beyond the bars 3 by an amount necessary for the production of the cross-bottom. FIG. 2 shows this guide bar system at one end of the tube. The apparatus mainly comprises a pair of suction tables 4, 5, the bottom table 4 is stationary and the top table 5 is so mounted in a support or bearing member 8 as to be vertically movable through the agency of guide rods 6, 7. The tables 4, 5 extend laterally beside the chain 1, so that the end of the tube S moves through between the table walls which are near one another and which are formed with suction orifices 9, the tube S being disposed between such walls when the chain is stationary as can be seen in FIG. 1. The length of the tables 4, 5 corresponds substantially to the width of the tube. The orifices 9 are disposed in a row near the end of the tube.

A driveshaft 10 mounted in the member 8 is coupled with the gripper chain drive so as to perform one complete revolution during one working stroke of the bottommaker. Mounted on shaft 10 is a thrust cam 11 whose operative movement is transmitted to the top table 5 via a roller-fitted lever 12 and a pull rod 13. The cam 11 raises the table 5 during the angle of rotation oz, corresponding substantially to the time when the tube is stationary near the pair of suction tables. The upwards movement of the table 5 is only a few millimetres. During the angle 3 of cam rotation, corresponding to the roof of the cam 11, the tube is conveyed by the chain 1, and during the angle 7 of cam rotation the top table 5 descends towards the next tube which has meanwhile been conveyed into the suction table region.

A hose 14 connects tables 4, 5 to a vacuum pump 15 and comprises a magnet valve 16 controlled by means of switch 17 and of a tappet 18 on lever 12; the arrangement is such that, when the lever 12 runs up on to the roof of the cam 11, the switch 17 stays closed during the angle 3, to re-open during the descent of table 5 through the angle v. Correspondingly, valve 16 keeps table 5 connected to pump 15 during the upward operative movement through angle a, while during angle [3 valve 16 connects table 5 to atmosphere. Once chain 1 has moved a tube S into the region of the two tables 4, 5, cam 11 lowers the top table 5 so that the same engages by way of its suction orifices 9 with the tube end and presses the same against the suction orifices in the bottom table 4. At the same time, tappet 18 and switch 17 open valve 16 so that the two tables 9 are connected to the pump 15 and suck and retain the layer near them of the end of the tube. Cam 11 then raises the top table 5 a few millimetres, corresponding to the large angle a, with the result that the layers are slowly disengaged from one another over the width of the tube by the same few millimetres. Because the layers are disengaged slowly in this way, there is sufiicient time for atmospheric air to enter the gap between the layers of the tube and equalise the pressure there to atmospheric pressure. Disengagement can be boosted by an injection of compressed air into the gap occurring as a result of initial disengagement, and this feature will be described in greater detail hereinafter with reference to the other embodiments.

Once the layers at the end of the tube have been satisfactorily disengaged from one another, valve 16 is changed over to disconnect tables 4, 5 from pump 15, whereafter, during the angle of rotation [-3 of cam 11, table 5 remains in its top end position and chain 1 conveys the initially opened tube, by an amount corresponding to the spacing or step t, into the region of a known kind of draw-on station A which, during the next stoppage of the chain, opens the tube rapidly, e.g. through the agency of two pivoted suction tables 19, 20, so that the cross-bottom can be laid.

As can be seen from FIGS. l and 2, the tables 19, 20 are in the form of vacuum beams each having a face defining a plurality of vacuum openings and arranged opposite the same face of the other beam.

The apparatus shown in FIGS. 3-7 is of use for continuous bottom-makers in which a moving gripper chain 21 moves transversely positioned tube portions S past various working stations. The apparatus mainly comprises a pair of stationary suction tables 22, 23 which extend in the direction a of tube conveyance near the tube ends; those walls of the table 22, 23 which are near one another are formed with suction slots 24, 25, visible in FIG. 5, diverge from one another by a few millimetres in the direction of tube conveyance, and are covered by suction belts 27, 28 which are formed with suction holes 26 and which rotate, in the direction a of tube conveyance, at the speed of conveyance of the tube ends passing through between them. Pipes 220, 230 connect tables 22, 23 to a vacuum pump (not shown). Belts 27, 28 run over drive pulleys 29, 30 and are guided accurately by means of deflecting pulleys 31, 32 and pairs 33, 34 of jockeys. As can be gathered from FIGS. 3-6, the tables 22, 23 are mounted on a bearing plate 35, which also receives the pulleys 29, 30, their coupling wheels 37, 38, a drive gear 36, the deflecting pulleys 31, 32 and the jockeys 33, 34. Through the agency of collars or bushes or the like 39, plate 35 is so mounted on guide rods 40 as to be movable transversely of the direction of conveyance of the tubes S, the guides 40 being secured in machine frame 41. As FIG. 6 shows, plate 35 can be moved by a screw-threaded spindle 42 which has a handwheel 43 at one end and which is engaged rotatably at its other end, by way of an adjusting ring 44, in a coupling member 45 secured to the plate 35. As FIG. 4 shows, the drive gear 36 is disposed on a bush or collar 46 which is mounted in plate 35, and which slides on a drive shaft 47 parallel to rods 40 and which is coupled -to shaft 47 by way of a key 48. Driveshaft 47 is mounted at both ends in frame 41 and is driven by the bottommaker drive via gear 49. Thanks to the plate 35, which can move in the direction indicated by an arrow 0, the complete disengaging facility can be adjusted for adaptation to different tube lengths .51 corresponding to the working programme of the bottom-maker.

As can be gathered from FIG. 5, an air nozzle 50 extends through plate 35 into the space between the two tables 22, 23 so that the air flow from the nozzle is directed into the gap between the two layers S1, S2 at the end of the tube S. The air line 51 can comprise a known kind of ionisation chamber 52 in which the compressed air passes over a high-voltage blow discharge path and thus becomes conductive. The ionised air helps to neutralise possible static charges of the tubes, such charges causing the layers to stick together tightly, more particularly at the tube ends.

Preferably, the belts 27, 28 are made of fibre-reinforced plastics and, as FIG. 7 shows, are formed on both sides with a perforation 53 engaged by matching teeth 54 at the periphery of the pulleys 29, 30 (FIG. 4), so that the belts 27, 2-8 are driven accurately and without slipping. As FIG. 7 shows, the belts 27, 28 are formed with rows of suction holes 55 which, as the belts 27, 28 move past the tables 22, 23, register with the suction slots 24, 25 therein. The length of the holes 55 is at most equal to the minimum tube width Sb for which the apparatus is designed. The imperforate intervals 56 of the,belts 27, 28 between the series of holes 55 are of the same length as the length l of the slots 24, 25. Consequently, the series 55 of holes are always covered by the layers of film at the end of the tube, and the suction slots 24, 25 remain covered by the imperforate zones 56 even when the holes 55 only partly cover the slots 24, 25. In the event of a tube being missing, the suction provided by the tables 22, 23 is fully operative for the preceding tube and for the immediately following tube.

Referring to FIG. 7, the gripper chains 21 move the tubes S (spaced apart by a distance t) between the belts 27, 28 so that the ends of the tubes register with the holes 55. As the belts 27, 28 and tube ends pass between the tables 22, 23, the holes 26 one by one come into register with the slots 24, 25, with the result that, as can be seen in FIG. 5, the layers S1, S2 of the tubes are sucked by the belts 27, 28 and retained as they pass by the suction slots 24, 25. Due to the divergence of the tables 22, 23 the layers S1, S2 start to be disengaged from one another at a side fold of the tube, the disengagement continuing gradually. Access for atmospheric air is therefore provided between such layers (cf. FIG. 3). The entry of air into the gap is boosted by nozzle 50 which provides a forcible injection of ionised air into the gap. At the exit end of the pair of suction tables, the suction of the suction belts 27, 28 ceases immediately their suction holes 26 leave the suction slots 24, in the tables 22, 23. The initially opened tube is therefore released from the suction belts 27, 28 and conveyed onwards by the chains 21 towards the drawing-on station B of the bottom-maker where the cross-bottom is rapidly drawn on and laid by a known pair of suction tables 59, 60 which swing in opposite directions on parallel cranks 57, 58. The

tables 59, 60 are in the form of vacuum beams each having a suction face arranged opposite the suction face of the other beam.

The apparatus shown in FIGS. 8 and 9 provides progressively disengagement or venting of the layers of film at the tube ends by means of a pair of suction rollers 61, 62 which rotate, in the direction a of tube conveyance, at the speed of conveyance of the tubes S, the ends of the tube passing through between the rollers 61, 62, the same rotating to opposite hands. The pair of suction rollers 61, 62 is mounted on a bearing plate 350 which, like the plate 35 shown in FIGS. 36, is displaceably mounted on the machine frame for adjustment of the apparatus transversely of the direction a to the various tube lengths S1 for which the bottom-maker is designed. Rollers 61, 62 are inter-connected via coupling gears 63, 64, one of which is driven via gearwheel 65 by the bottommaker drive. The rollers 61, 62 are formed on their periphery with a series of radial suction passages 66 communicating with circularly disposed suction channels 67 inside the suction roller, the channels 67 extending parallel with the roller axis and extending to an end face of the roller. In each roller the circle of suction channel outlets 67 is covered by a control ring 68 which is in sealing-tight engagement with the suction roller end face. Each ring 68 is pressed against its end face by springs 69 and secured against rotation by a locking pin 70 and is formed near the circle of outlets of the channels 67 with the recess 71 which extends just to the extent of a small angle m away from the contact plane E-E between the pair of suction rollers in their direction of rotation and which is connected via suction line 72 to a vacuum pump (not shown). The angular range a of recess 71 therefore corresponds to the suction roller suction zone along which the layers S1, S2 of the tube end are retained and moved by the suction rollers. The periphery thereof is equal to the spacing t at which gripper chains 72 advance the tubes in the bottom-maker. Of this periphery only a portion corresponding to the maximum tube width Sb to be dealt with is formed with radial suction passages 66, the remainder of such periphery, such remainder corresponding to the angular region B in FIG. 8, being imperforate. The spacing t and therefore the suction roller periphery are so devised that the angular range B is at least equal to the angular range a. The suction roller drive and the gripper chain drive are so interconnected that the suction passages 66 in the two suction rollers roll on the tube exactly at the leading side fold thereof, the imperforate leading peripheral portion [3 ensuring full suction immediately the first pasage 66 engages with the layers S1, S2 by preventing the external air from entering recess 71 in the rings 68.

When the ends of the tube S being conveyed by the chain 72 pass between the rollers 61 and 62, the layers S1, S2 are progressively plucked apart from another by a few millimetres along the zone or angular region on, to be released after having passed through the suction zone. To boost this disengaging or venting step, air is blown from an air line 73 near the suction zone between the disengaged layers; if required, such air can first be ionised in an ionisation chamber 74.

After its ends have disengaged from one another, the tube S is conveyed by the chains 72 to a known station for drawing-n and laying the bottom, such as is provided, for instance, in the embodiment shown in FIG. 3.

The apparatus hereinbefore described can, if bottomfolding is required at both ends of the tube, be provided on both sides of the bottom-maker.

I claim:

1. Apparatus for opening the end ,portions of flattened tubes of flexible plastic sheet material, comprising, in combination: means for conveying the flattened tubes continuously along a conveying path in a conveying direction at a uniform rate, a pair of stationary suction tables arranged along and on opposite sides of the conveying path and extending in said conveying direction, said suction tables having opposed faces which diverge by a few millimeters in the conveying direction, a pair of suction belts formed with suction holes, means for moving the belts in the conveying direction and in engagement with the opposed faces of said suction tables and on opposite sides of the tubes being conveyed, said belts being arranged to engage the layers of sheet material which form the opposite sides of the tubes and partially open said end portion due to the diverging opposed faces and suction means arranged downstream of said suction tables for rapidly opening said partially opened end portion completely, said suction means having a pair of vacuum beams each having a suction face arranged opposite the suction face of the other of said beams, said beams being mounted to revolve in opposite directions and adapted to 8 engage the layers of said end portion so as to completely open said end portion.

2. The apparatus of claim 1 wherein groups of suction holes are formed in said suction belts at positions corresponding to the positions of said suction slots in said suction tables, each group being of a length equal to the smallest tube width to be dealt with, and said groups being spaced from one another by a distance at least equal to the lengths of said suction slots.

3. The apparatus of claim 2 including a bearing plate supporting said suction tables and said belts, and means for adjusting the position of said bearing plate transversely of the direction of conveyance of the tubes.

References Cited UNITED STATES PATENTS 1,678,869 7/1928 Morrison 317-2(.1) 2,202,431 5/1940 Rohrbacher 93-28 2,281,516 4/1942 Royal 53-386 3,086,145 4/1963 Hood 317-2 3,222,844 12/1965 Smith et al 53-228 X 3,287,879 11/1966 Miller, Jr 53-386 X 3,381,446 5/1968 Marchand 53-386 X 3,427,780 2/1969 Bock 53-386 X 3,446,121 5/1969 Achelpohl 9328 3,503,179 3/1970 Jean-Louis Pierre 53-386 X 3,190,049 6/1965 Van Der Meulen 53-187 X 3,330,093 7/1967 Schorer 53-189 3,077,147 2/1963 Finke 93-23 FOREIGN PATENTS 1,149,367 5/1963 Germany 271-11 THERON E. CONDON, Primary Examiner H. M. CULVER, Assistant Examiner US. Cl. X.R. 93-28, 53(SD) 

